Production of submarine signals and the location of suemarine orjects



PRODUCTION OF SUBMARINE SGNALS AND THE LOCATION OF SUBMARXNE OBJECTSFiled May 19, 1917 2 Shetsasheai; E

C. CHHLOWSKY ET AL PRODUCTION OF SUBMARINE SIGNALS AND THE LOCATION 0FSUBMARINE OBJECTS Filed May 19, 1917 2 ShOOis-Sheet 2 Patented Oct. 23,1923.

UNITED STATES- PATENT CFFICE.

PRODUCTION 0F SUBMARINE SIGNALS AND THE LOCATION OF SUBMARINE OBJECTS.

Application led May 19, 1917. Serial No. 169,804.

To all whom t may concern.'

Be it known that we, CoNsTAN'rIN CH1- LowsKY and PAUL LANGEVIN, theformer a citizen of the Government of Russia and the latter a citizen ofthe Republic of France, both residing in Paris, France, have inventedcertain new and useful Improvements in the Production of SubmarineSignals and the Location of Submarine Objects, of which the following isa specification.

Acoustic methods have before been proposed to detect at a distance inWater obstacles dangerous to navigation, Such as mines, submarines,torpedoes, rocks, ice- -bergs, ships in foggy weather, and the like.

But their efficiency is greatly reduced as the sound emitted spreads inall directions andrapidly weakens as the distance increases; on theother hand the reception of the sonorous echo produced by the obstacleindicates but with difiiculty the position of Sallie.

The process and apparatus which are the subject of the present inventiondo not present these defects, and moreover permit of producing directedsecret signals for military purposes.

The method consists in producing'under water ultra-sonorous mechanicaloscillations. that is to say, of a very high frequency, by thesynchronous vibrating motion of all the polnts of a transmittingsurface. whose linear dimensions are large in proportion to the Wavelength in the water of the emitted oscillations. f

Under these conditions, the energy emitted remains almost completelylocalized in a transmitting cone, the axis of which is normal to theradiating surface and whose opening or angle will be relatively smalleras the ratio between the area of the transmitting surface and the wavelength becomes larger. For a transmitting surface of a diameter d, thesine of the opening angle z of this cone (half the angle ofthe apex)will be given by the formula:

)t sln. a==0.6

)t being the wave-length in the water.

The ultra-sonorous beam thus obtained is similar to the luminous beam ofa searchli'ght and can be used, either to produce signals or to detectthe presence of obstacles by the observa-tions of the diii'used orreflected radiation.

For practical purposes, the frequency of the oscillations used will befrom 50,000 to 200.000 per second with wave-lengths of 3 to 0.7centimetres (the velocity of propagation of the elastic or mechanicalwaves in water being about 1500 metres per second), and the diameter ofthe transmitting surface from 30 to 100 centimetres.

Oscillations of greater frequency are too rapidly absorbed in waterowing to its viscosity and slower oscillations would glve too openbeams; nevertheless in certain cases, lower frequencies can be used witha transmitting apparatus of a larger diameter. Higher frequencies can beemployed at shorter distances.

To obtain a synchronous vibration of the whole of the transmittingsurface, the invent1on consists in the use of electrical, oscillationsof high frequency, such as are produced for wireless telegraphy ortelephony, and making use of the mechanical actions produced b electricor magnetic fields to transform t e energy of said electricaloscillations into ultra-sonorous vibrations with a frequency double thatof the electrical oscillations, these actions exerting themselvessynchronously and evenly on the whole of the transmitting surface.

Either maintained electrical oscillations can be used (produced byalternators, speaking arcs or hcterodyne lamps) or trains of dampedoscillations obtained by means of sparks.

The mechanical vibrations thus obtained will act on the receivingapparatus (microphones or parts similar to the transmitting apparatus)and will produce electrical oscillations with a frequency equal totheirs, which will be revealed by a known apparatus such as those usedin wireless telegraphy.

The location of obstacles is obtained in direction by giving to thetransmitting surface the position necessary to have an echo of maximumintensity, and in distance by observing the tim etween the transmissionof a signal and the return of the echo produced on the obstacle.

The invention will be described with reference to the accompanyingdrawings which illustrate more or less diagrammaticallyboth the theoryand practice of the invention.

Fig. 1 represents in section a transmitting apparatus having an electricfield.

Fi 1n is a view on a larger scale in whic the ratio of the dimensionshave been preserved, of the condensers shown in Fig. 1.

Fig. 1b is a view similar to Fig. 1 showing a slight modification. A

Fig. 2'l is a View on a larger scale in which the ratio of thedimensions have been preserved, of a portion of a modified form of aparatus according to the in vention. t

`igs. 2, 3, 3 and 4 show various modifications of apparatus having anelectric field.

Figs. 5 and 6 represent in plan and in section a transmitting apparatushaving a magnetic field.

igs. 7 and 8 are diagrams of the connections of apparatus havingelectric and magnetic fields respectively.

Fig. 9 is a receiving apparatus with an electric field showing thediagram of connections.

Fig. 10 represents a horizontal section through a chamber filled withwater containing the transmitting apparatus.

Fig. 11 represents a horizontal section` ofv a chamber with areceivingapparatus and a concave mirror.

Fig. 12 represents the same receiving chamber with a lens instead of themirror shown in Fig. 11.` 4

Fig. 13 represents the horizontal section of an alternative arrangementof transmitting apparatus placed at each side of the bow of the ship.

In the type of transmitting apparatus shown in Fig. 1, thetransformation of electrical energy into mechanical energy is obtainedby means ofthe electro-static attractions in a condenser forming part ofan oscillating circuit. The power of the elastic oscillations emitted isdetermined by the amplitude of the variations of the electric field inthe condenser.

The condenser is composed of a metallic insulated plate a of 30 to 100centimeters, placed in an insulating support g, and maintained by thepoints of support c at a very short distance '(1 to 10 microns) from athin plate Zi of metal or of insulatzing material. The plate a may, ifdesired,

be non-metallic and have a metallic coating on its surface facing b.

The opposite side of b being in contact with the water, this plate banswers freely to the periodical electrostatic attraction of the platea, either by its bending between its points of support, or by thegreateror less embedding of these in the elastic substance of the platesa or b. The smaller the distance between a and Z the greater will be theefficiency of the apparatus provided that said distance remains greaterthan the amplitude of the vibrations of b.

The late a is connected to one of the poles o the electric circuit il;the plate b to the other pole 2.

In order to obtain the freedom of vibration by the embedding of thepoints of support in one of the plates, one of said plates must consistof a slightly elastic substance, such as ebonite, ivory or the like,where the other plate is of metal, otherwise the condenser plate must becovered with a layer of a similar slightly elastic substance with ametal coating on its surface to permit of the charging of the condenserand the action ofthe electric field.

Alternatively the points of support may be very thin and consist eitherof lines or points of varnish or of mica strips or washers. The totalsurface of the points of sup* port must be fairly small so that theeffort of attraction permits of their yielding.

In order that the condenser may carry the high electric fields (superiorto 106 volts per centimeter of distance between the plates) which arenecessary for the transmission of powerful elastic waves (of the valueof a watt per square centimeter) three processes can be made use of 1.The condenser plates may be covered with a coating of platinum, gold orthe like. able to support in a vacuum at short distances very highelectric fields, and a very high vacuum of four ten-thousandths of a mm.of mercury may be kept up between the plates. This Avacuum is notnecessary and the atmospheric pressure can be maintained. if thedistance between the plates is sufficiently small,\.the potentialdifference employed varying proportionally with this distance.

2. The production of the disruptive discharge can be prevented bycovering the nietallic surfaces with a thin coating of insulatingmaterial such as mica, cellulose-acetate, or the like, and havingbetween them a vacuum, or not, according to their distance.

3. As shown in Fig. 2, a thin mica dia'- phragm b can be used, or adiaphragm of any other elastic insulating material, in l contact, withthe water, acting at the same time asa vibrating plate and as insulationfor thecondenser, with or without a vacuum between the diaphragm b andthe plate a; in this case, the water forms the exterior charge-bearer ofthe condenser, and the points of support c separating the mica diaphragm.7) from the plate a can either be inetallic or insulating.

T he vacuum can be made through a tube f with an opening of smalldiameter in the centre of the insulated plate or in the periphery ofsame. An insulating substance r/ is run behind the plate-and around thesides of the condenser. The plate a is connected lll() to one of thepoles of the electric circuit z", the other pole 2 dipping into thewater with the diaphragm b.

The modification of the apparatus shown in Fig. 3 consists of asymmetrical diaphragm made of two thin insulating sheets b1, b2 of mica,glass or the like, joined at their edges and separated by the points ofsupport c in the space in which their vibration would be free. A vacuumcan also be made between them when the sheets b1, b2 are of glass or thelike.

One side of the diaphragm would bein contact with'the salt water inwhich would be produced a radiating surface, formed by the exteriorplate of the condenser fed by 2, the other side being in contact with alayer of a liquid insulated conductor k (salt water, mercury, or thelike) forming the interior plate of the condenser fed by 1 and a.

The diaphragm of the condenser in contact with the water may consist ofa metallic plate 3a, the thickness of which is equal to the halfwavelength of the longitudinal elastic vibrations in the substance ofthe plate employed. This plate vibrates in the direction of itsthickness (that is to say, by contraction and dilation, the faces of theplate approach and move away one from the other) and acts upon the waterby its external face with an amplitude and periodicity equal to that ofthe electrostatic attraction exerted on its internal face by theelectric field of the condenser.A

This interior face of the diaphragm may, or may not, be covered with aninsulating layer b3 to prevent a disruptive discharge. Having a platewith a thickness of half a wave-length permits of reducing the number ofpoints of support between itself and the insulated plate owing to itssmaller fiexure; the electric oscillations employed are required t0 havethe same period as that of the vibration of the diaphragm.

The property which ebonite possesses of not giving any notablereflection of the longitudinal elastic waves on its separation surfacewith the water, permits using a plate of ebonite b (Fig. 4) in contactwith the water as a plate of any thickness (vibrating in the directionof its thickness)with a metallic coating on its interior face formingthe exterior plate of the condenser fed by 2 and separated from theinsulated plate a fed by 1 by suitable insulating supports c.

,In this case it is not necessary that the frequency of the transmittingvibrations should be in resonance with the vibrating exterior plate inthe direction of its thickness, and any frequency may be emitted aswlith the apparatus having a thin vibrating p ate.

The transmitting or receiving apparatus permitting the use of magneticaction is shown in Figs. 5 and 6 in which k is a plate of thin soft ironlaminations on the surface of which is arranged in a zig-zag shape aninsulated copper wire l carrying an electric current of very highfrequency; at a short distance from this plate and separated b somepoints of support, there is a thin sott iron plate m having its exteriorface in contact with the water.

The diagram of connections is given in Fig. 7, for the apparatusutilizing electrostatic action, and in Fig. 8 for that making use ofmagnetic action. K

In the first case, the transmitting condenser a, b has the function ofcapacity in the oscillating circuit II excited by induction by means ofa primary coil I; and in the second case (Fig. 8) the winding Z of theplate lc forms a part of the self-induction of the oscillating circuitII provided with a suitable capacity j and excited by the pr'.- marywinding I.

For the receiving device, a. microphone may be used providing that itsvibrating plate is in contact with the Water and has points of supportthe resistance variations of which are caused by the arrival ofultrasonorous waves, producing periodical variations of equal frequencyin the current produced through this microphone by a constantelectromotive force.

These variations produce electric oscillations ina tuned circuit` eitherdirectly, if this circuit is placed between the microphone terminals` orby induction of the microphone is in series with the primary coil of atransformer` of .which the secondary winding is formed by theself-induction of the oscillation circuit.

lVth the receiving apparatus, Fig. 9, the energy of the incidentelectric waves may be transformed into electric oscillations byreceiving these on a condenser a, b similar to those used fortransmission, but the plates of which mav be brought closer (about amicron) due to the feeble amplitude of the elastic displacements. Asource of constant electromotive force E keeps the condenser j charged(an optimum value exists for this) andthe variations of capacityproduced by the, incident waves cause electric oscillations in a tunedoscillating circuit of which this condenser a. b forms a part. Theelastic energy may be absorbed and converted into electric energy. ifthe electromotive force of the source E has an optimum value asindicated below. Then the incident elastic waves are absorbedl by thesurface of the condenser a, 7) and do not undergo any reection in thiscase.

The electric oscillations will be registered by any kind of detector,for example, a vacuum tube amplifier d. the connections of which withthe oscillating circuit may be Varied according' to the method adoptedin wireless telegraphy.

llt)

The optimum value E of the electromotive force is given by the formula:

E @a1/Tas where (o is equal to the wave period or 21m where -n is thecyclic frequency of the wave and r1-3.1416, (Z the distance between theplates of the condenser a, I), Fig. 9; S the surface area of theseplates; p the density of -salt water; V the velocity of propagation ofsound in this medium; R the ohmic resistance of the selfinduction coil nconnected to the condenser to obtain a circuit in syntony with thefrequency of the waves in use.

In Fig. 9, j is a condenser of large capacity presenting to the passageof the oscilla- .tions created in the electric circuit an 1m pedancemuch smaller than that. of the battery E; this condenser is mounted in acascade `arrangement with ai, b and the two condensers j and a I) takentogether represent the capacity of the oscillating circuit.

A receiving apparatus' similar to the one suggested for magnetictransmission (Figs. 5 and 6, may be used if the copper wire carries acurrent from a constant source. The conversion of the mechanical energyof the incident waves into electric oscillations in a tuned circuit ismade by means of the variations of self-induction of thel apparatus dueto the periodic movementof the exterior plate in contact with the water.The transformation is effected tions if the continuous source possessesa convenient optimum electromotive force.

To protect the transmit-ting and receiving apparatus against the shockof the waves, these will be. placed in a box with thick ebonite walls 7-(Fig. 10), making use. of the property of this substance as previouslyindicated. This may, for instance, be placed at the front of the ship-V, held .by the brackets u, the exterior shape ofthe solid being that ofsmallest resistance. The interior of the box with ebonite sides shouldbe filled with water and the transmitting apparatus s (Fig. 10) may beplaced in different direct-ions, for example around the vertical axisprojecting at t.

'l`o increase the sensitiveness of the re eeiver. the receivingapparatus may be placed in the focus of a concave mirror g of a largesurface (Fig. 11) or in the focus of a lens (Fig. 12) of a largediameter constituted by a cover o transparent to the waves (ebonite, forexample) filled with a liquid (ether, alcohol or the like) in Which thevelocity of propagation will be less than in water. This lens or mirrormay be turned aroiuid a pivot t so that its axis passes through thesource or through the obstacle in such manne-r that its optical axisshall be situated in the direct-ion of the source or the obstacle.

T o avoid the transmitting surface having in the best condi-Y veryconsiderable dimensions when very high powers are emitted, and to retainthe faculty to change the direction of the beam as desired, this surfacemay be divided up into independent sets S (Fig. 13) placed in parallel,turning;r round parallel pivots t, on condition that the wave lengthsarevaried when used in setting these sets, so that the normal distancebetween two transmitting elements is a complete multiple of the wavelength.

Under these conditions, the waves sent out by these sets in directionsnormal to their planes are kept in synchronism. As stated previously,this apparatus may be placed in anfebonite cover 1 and fixed to thesides of the ship V.

The methods and apparatus described may be applied to the followingcases 1. Exchange of directed submarine signals between ships, orbetween ships and coast stations, or between coast stations. Thesesignals have the advantages of optical signals and are superior in thatthey cannot be hindered by fog or haze.

2. In establishing ultra-sonorous stations with transmitting surfaces ofal very large diameter.

3. Searching for and locating submarine obstacles by means of periodicand tuned transmissions during the interval of which the return of anecho is perceived.

The relative motion ofthe obstacle and the observation post may bedetermined by applying Dopplers method, that is to'say, by observing thechange of frequency due to the movement ofthe obstacle, particularlysensitive in the sonorous beats obtained between the receivedoscillations which are due to vibrations reflected by the obstacle,`andthe oscillations produced by an adequate source, these latteroscillations having a fi equency which is approximately that of thereceived oscillations and may be produced by a heterodyne lamp.

4. Searching and locating submarine objects by the ultra-sonorous shadowwhich they give on the receiving apparatus if their dimensions are largein proportion to the wave length in the Water of the vibrationsemployed.

Having thus described the nature of the said invention and the bestmeans we know of for carrying the same into practical effect, weclaim 1. Means for producing and receiving directed beams ofultra-sonorous rays which are transmissible in ordinary matter,comprising a. plate having a large diameter in proportion to the Wavelength of the elastic vibrations emitted, and means for synchronouslyvibrating the entire surface thereof, said plate having a diameter of to100 centimeters and said waves having a length between 3 and .7centimeters.

resistthe necessa reduction of the 2.' Means for producing and receivingdirected beams of ultra-sonorous rays 1n water,

Vcomprising a plate having a large diameter in proportion 'to the wavelength of the' rected beams of ultra-sonorous rays in water,

comprising a plate having a large diameter in proportion to the wavelength of the elastic vibration to be emitted in the water, and a fieldof force equally distributed over the surface of the plate for settinginto to and fro motion the whole surface of said plate in contact withthe water, said field of force being produced by electrical oscillationsof high frequency, said plate having a diameter of 30 to 100 centimetersand sai waves having a length between 3 and .7 centimeters.

4. An apparatus to produce and transmit ultra-sonorous beams in water,which comprises a plane condenser of great surface having an insulatedmetallic plate and a thin/plate in contact with water the condenserbeing part of an electric circuit of high frequenc the periodic electricfield of great amplitude produced between the two plates causing thethinner one to vibrate, and means enabling the condenser to intenseelectric field by istance between the metallic and insulating plates ofthe condensers, said plate having a diameter of 30 Vto 100 centimetersand sald waves having a length between 3 and .7 centimeters.

5. An apparatus to produce and transmit ultra-sonorous beams in Water,which comprises a plane condenser of great surface having an insulatedmetallic plate and a thin plate of any elastic insulating substance incontact with the salt water, said plate acting as the exterior diaphra mof the condenser, said plate resting on t e insulated plate by means ofinsulating or conducting supports between which it can vibrate freely,the condenser being part of an electric circuit of high frequency, theperiodic electric field of reat amplitude produced between the twoplates causing the thinner one to vibrate, and means enabling thecondenser to resist the necessary intense electric field by reduction ofthe distance between the metallic and insulatin plates of this condenserand keeping up a thigh vacuum in the intervals, said plate having adiameter of 30 to 100 centimeters and said waves having a length between3 and .7 centimeters.

6. Apparatus according to claim 4, having, in place of the vibratingplate therein specified, as a vibratin the thickness of a ha wave lengthin resonance with the elastic vibrations emitted.

7. Apparatus according to claim 4, having, in place of the vibratingplate therein specified, as a vibrating plate, a plate of ebonite of anythickness with a metallic coating, the product of the density by thevelocity of the sound being about the same in this substance as in saltwater.

8. Apparatus as claimed in claim 4, the diaphragm being a substance witha thick-` ness of a quarter wave length in which the product of thedensity by the velocity of the vibrations are inferior to that of saltwater, whereby the emitted electric energy for a given amplitude of theelectric or magnetic fieldl of the apparatus. is increased.

9. In apparatus asclaimed in claim 4, several sets of apparatus inparallel, the freuency being varied in the setting so that t e normaldistance between any two of them always remains equal to a whole numberof wave lengths in the water.

AIn witness whereof we have hereunto signed our names in the presence oftwo subscribing witnesses.

CONSTANTIN CHILOWSKY. PAUL LANGEVIN. Witnesses:

Cms. P. Pnnssnr,

Hmm: CARTIER.

plate, 'a plate of

